The label on a candy bar says 400 Calories.  Assuming a typical efficiency for energy use by the body, if a 57 kg person were to use the energy in this candy bar to climb stairs, how high could she go?

A weightlifter curls a 26 kg bar, raising it each time a distance of 0.65 m . How many times must he repeat this exercise to burn off the energy in one slice of pizza?  Assume 25% efficiency. Energy content of one slice of pizza is 1260  kJ

A heat engine takes in 2500J and does 1500J of work.   a) How much energy is expelled as waste?            b) What is the efficiency of the engine?

A 46-kg woman eats a 522 Calorie (522 kcal) jelly doughnut for breakfast. (a) How many joules of energy are the equivalent of one jelly doughnut? 2.19 Your response differs significantly from the correct answer. Rework your solution from the beginning and check each step carefully. J (b) How many steps must the woman climb on a very tall stairway to change the gravitational potential energy of the woman-Earth system by a value equivalent to the food energy in one jelly doughnut? Assume the height of a single stair is 15 cm. 3.22 X Your response differs significantly from the correct answer. Rework your solution from the beginning and check each step carefully. stairs (c) If the human body is only 26% efficient in converting chemical potential energy to mechanical energy, how many steps must the woman climb to work off her breakfast? 8.4 X Your response is off by a multiple of ten. stairs

An ideal heat engine operates between 177 degree C and 27 degree C. If the engine takes 5*1000000 J of heat from the source, how much work does it perform?

A hot plate is used to transfer 400 cal of heat to a beaker containing ice and water. 500 J of work is also done on the contents of the beaker by stirring. What is the increase in internal energy of the ice water mixture? And how much ice melts in this process?

The engine of a large ship does 1.97  1010 J of work with an efficiency of 8.60%. (a) How much waste heat is produced? (b) How many barrels of fuel are consumed if each barrel produces 6.00  109 J of heat when burned?

As a gasoline engine is running, an amount of gasoline containing 18,500 J of chemical potential energy is burned in 1 s. During that second, the engine does 3,700 J of work. (a) What is the engine's efficiency (in percent)?  % (b) The burning gasoline has a temperature of about 4,100°F (2,500 K). The waste heat from the engine flows into air at about 90°F (305 K). What is the Carnot efficiency (in percent) of a heat engine operating between these two temperatures?  %

Explain with the formulas please

How much energy would you consume daily if you kept 3 lightbulbs of 25 watts on all day long?.